1. Field of the Invention
The present invention relates to a touch sensor switch.
2. Related Art
In vehicles, for example, switches each comprising a push-button or a touch sensor for starting and stopping of an operation of a mounted electronic device or an engine are used.
As one example of a conventional switch using the touch sensor, JP-A-7-272604 discloses a switch in which a conductive touch portion is provided on a surface of a tile, a touch sensor circuit is provided on a back side of the tile, the touch sensor circuit and the touch portion are connected to each other by a conductive rubber or a lead wire, and the touch sensor circuit detects an electrical alteration when a finger contacts with the touch portion to conduct an ON/OFF operation, has been known.
Further, a switch in which a push-button switch and a touch sensor are mounted on the same board is also used. In this case, the touch sensor comprises a conductive film provided on a surface of a push-button (knob) by spattering or the like. The conductive film is connected to a wiring pattern on the board by a harness.
Further, as one example of a conventional switch, in which the ON/OFF operation is conducted without using a mechanical switching element, is disclosed by JP-A-5-38735. In such a conventional switch, a conductive contact rubber is interposed between a lower terminal of a push-button and a printed circuit board, an expanded portion of the conductive contact rubber descends against its elasticity when the push-button is pushed, a contact portion of the expanded portion contacts with a wiring pattern on the printed circuit board so that the switch is turned on.
However, in the conventional switch comprising the touch sensor, since the harness is used for the connection between the conductive film and the wiring pattern of the board, metal fatigue progresses in accordance with an increase in usage frequency of the push-button or a stroke level of the harness. Since the harness is easily broken, it is not possible to enhance the reliability. Further, there are problems for productivity, cost reduction and the like, since assembling steps are increased in accordance with an increase in the number of parts.
Further, according to the structure disclosed by JP-A-5-38735, since the conductive contact rubber is used the for switch, the harness is used as a connecting means, so that it is difficult to fabricate a composite switch by combining the touch sensor and the push-button switch.